The objective of this study was to determine whether the bearing surface is a risk factor for revision after late dislocation in total hip arthroplasty (THA). Data from primary THAs were extracted from the New Zealand Joint Registry over a 13-year period. The mean age of patients was 68.9 years; 53.2% were female. The surgical approach used was posterior in 66% of THAs, lateral in 29% and anterior in 5%. There were 53,331 (65.1%) metal-on-polyethylene THAs, 14,093 (17.2%) ceramic-on-polyethylene, 8,177 (10.0%) ceramic-on-ceramic, 461 (0.5%) ceramic-on-metal, 5910, and (7.2%) metal-on-metal. The primary endpoint was late revision for dislocation, with ‘late’ defined as greater than one year post-operatively. 73,386 hips were available for analysis. The overall revision rate was 4.3% (3,130 THAs), 1.1% (836) were revised for dislocation. Only 0.65% (470) hips were revised for dislocation after the first post-operative year. The unadjusted hazard ratios (HR) showed significantly higher rates of revision for dislocation in ceramic-on-polyethylene (HR 2.48; p=0.001) and metal-on-polyethylene (HR 2.00; 95% p =0.007) compared to ceramic-on-ceramic. However, when adjusted for head size, age and surgical approach, only ceramic-on-polyethylene (HR 2.10; p=0.021) maintained a significantly higher rate of revision, whereas metal-on-polyethylene approached significance (HR 1.76; 95% p = 0.075). In New Zealand, dislocation is the most common reason for revision, ahead of aseptic loosening of the acetabular component. The relationships between bearing materials and risk of revision for late dislocation is controversial. However, in this study ceramic-on-ceramic shows lower risk rates for revision than other bearing surface combinations. Low wear and less debris, limited peri-articular inflammatory reaction and an healthy fibrotic pseudo-capsule are potential factors determining long-term stability of the hip joint.
Acetabular fractures management is controversial since, despite a good anatomical reduction, clinical outcome is not satisfactory very often and the probability of a total hip arthroplasty (THA) is high. Surgical treatment include long operating times, large approach, blood loss, neural and muscle damage, and a high risk of failure and secondary osteoarthritis related to bone necrosis, cartilage damage, and bone loss. We hypothesized that the acetabular fracture management affected the clinical and radiological outcome of THA after posttraumatic arthritis. We compared 49 patients (49 hips) initially treated conservatively followed some months later by THA in conjunction with acetabular reconstruction (group 1); and 29 patients (29 hips) who had undergone THA after a failed osteosynthesis (group 2). There were more associated fractures according to Letournel in group 2. The mean age was 59.3±15.8 years for group 1 and 52.9±15.2 years for group 2. The mean delay between fracture and THA was 75.4±5 months for group 1 and 59.4±5 for group 2. The mean follow-up was 11.7 in group 1 and 10.2 in group 2. Preoperative bone defect was similar. We used bone autograft in 13 hips (26.5%) in group 1 and four (13.6%) in group 2. We used acetabular reconstruction plates in 2 hips with a pelvic discontinuity in group 1. Complications, clinical outcome according to Harris Hip Score, and radiological reconstruction were compared. Two-way ANOVA with repeated measures were used for comparison.Introduction
Materials and Methods
In the year 1977 we started to use ceramic on ceramic total hip (Ceraver*). The prosthesis was cemented on both sides. Ceramic was medical grade with relative large grains and high porosity. The stem was made of titanium alloy smooth and oxidized. In 1990 we published the results of 86 hips in 75 patients who were less than 50 years of age at time of operation (1). Recently we tried to reach the same patients, looking specifically to those who could have more than 20 or 30 years follow-up. This study design included all patients operated between 1977 and 1986 and having less than 50 years of age at time of surgery. Eighty six hips in 75 patients, 34 females and 41 men. Mean age was 43 (from 18 to 50) nine had a BMI in excess. 66 hips were performed primaries while 20 consisted in revision procedure including 6 total hip revisions, 5 resurfacing, 4 single cup, 3 hemiarthroplasty, and 2 acetabula fractures. Four of these had a past history of infection. Preoperative diagnosis were secondary osteoarthritis in 41, AVN in 26, primary OA in 3, Rheumatoid arthritis in 12, tuberculosis in 2 and hemophilic in two.Introduction
Material and methods
Starting in 1977 a new cemented stem made of titanium alloy (with vanadium) was designed regarding some principle: rectangular shape, smooth surface covered with thin layer of titanium oxide, filling the medullar cavity. As a consequence: a thin layer of cement. It was designed with a collar. Initial Cementing technique used dough cement, vent tube and finger packing; then we applied cement retractor low viscosity cement and sometimes Harris Syringe. At the moment we went back to initial technique plus a cement retractor made of polyethylene. Many papers looked at long term follow up results depicting about 98 to 100 percent survivors at 10 years and 95 to 98% at 20 years (Hernigou, Hamadouche, Nizard, El Kaim). Clinical as well as radiological results are available. Radiological results depicted some radiolucent lines that appeared at the very long term. They could be related to friction between the stem and the cement. As advocated by Robin Ling, he called “French paradox” the fact that if a cemented prosthesis is smooth and fills the medullary cavity, long term excellent results could be expected. This was the case with stainless steel Kerboull shape, the Ling design (Exeter)and the Ceraver design. The majority of these stems were implanted with an all alumina bearing system. And in some occasion, when revision had to be performed, the stem was left in place (108 cases over 132 revisions) Our experience over more than 5000 stems implanted is outstanding (see figure 1: aspect after 30 years). Discussion other experience with cemented titanium stem were bad (Sarmiento, Fare). We suspect that this was related either to the small size of this flexible material, or to the roughness of its surface. If one uses titanium cemented stem it must be large enough and extra smooth.
